From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78018C433EF for ; Mon, 31 Jan 2022 18:56:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244272AbiAaS43 (ORCPT ); Mon, 31 Jan 2022 13:56:29 -0500 Received: from alexa-out-sd-02.qualcomm.com ([199.106.114.39]:20151 "EHLO alexa-out-sd-02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232915AbiAaS41 (ORCPT ); Mon, 31 Jan 2022 13:56:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1643655388; x=1675191388; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=kaj4j/1RJd1d+1eIhFnvpmOvCmlsLKxbfI0yMzUfdds=; 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Feb 2022 00:26:18 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.1.2 Subject: Re: [PATCHv9 0/5] lib/rwmmio/arm64: Add support to trace register reads/writes Content-Language: en-US To: Will Deacon , Catalin Marinas , Arnd Bergmann , Marc Zyngier , Steven Rostedt CC: gregkh , , "Trilok Soni" , , , References: From: Sai Prakash Ranjan In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Arnd, Steve On 1/24/2022 12:03 PM, Sai Prakash Ranjan wrote: > Generic MMIO read/write i.e., __raw_{read,write}{b,l,w,q} accessors > are typically used to read/write from/to memory mapped registers > and can cause hangs or some undefined behaviour in following cases, > > * If the access to the register space is unclocked, for example: if > there is an access to multimedia(MM) block registers without MM > clocks. > > * If the register space is protected and not set to be accessible from > non-secure world, for example: only EL3 (EL: Exception level) access > is allowed and any EL2/EL1 access is forbidden. > > * If xPU(memory/register protection units) is controlling access to > certain memory/register space for specific clients. > > and more... > > Such cases usually results in instant reboot/SErrors/NOC or interconnect > hangs and tracing these register accesses can be very helpful to debug > such issues during initial development stages and also in later stages. > > So use ftrace trace events to log such MMIO register accesses which > provides rich feature set such as early enablement of trace events, > filtering capability, dumping ftrace logs on console and many more. > > Sample output: > > rwmmio_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 > rwmmio_post_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 > rwmmio_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 addr=0xfffffbfffdbff610 > rwmmio_post_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 val=0x0 addr=0xfffffbfffdbff610 > > This series is a follow-up for the series [1] and a recent series [2] making use > of both. > > [1] https://lore.kernel.org/lkml/cover.1536430404.git.saiprakash.ranjan@codeaurora.org/ > [2] https://lore.kernel.org/lkml/1604631386-178312-1-git-send-email-psodagud@codeaurora.org/ > > Note in previous v4 version, Arnd suggested to benchmark and compare size with callback > based implementation, please see [3] for more details on that with brief comparison below. > > > **Inline version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y** > $ size vmlinux > text data bss dec hex filename > 23884219 14284468 532568 38701255 24e88c7 vmlinux > > **Callback version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y** > $ size vmlinux > text data bss dec hex filename > 24108179 14279596 532568 38920343 251e097 vmlinux > > $ ./scripts/bloat-o-meter inline-vmlinux callback-vmlinux > add/remove: 8/3 grow/shrink: 4889/89 up/down: 242244/-11564 (230680) > Total: Before=25812612, After=26043292, chg +0.89% > > [3] https://lore.kernel.org/lkml/466449a1-36da-aaa9-7e4f-477f36b52c9e@quicinc.com/ > > Changes in v9: > * Use TRACE_EVENT_CLASS for rwmmio_write and post_write (Steven Rostedt) > > Changes in v8: > * Fix build error reported by kernel test robot. > > Changes in v7: > * Use lib/ instead of kernel/trace/ based on review comment by Steven Rostedt. > > Changes in v6: > * Implemented suggestions by Arnd Bergmann: > - Use arch independent IO barriers in arm64/asm > - Add ARCH_HAVE_TRACE_MMIO_ACCESS > - Add post read and post write logging support > - Remove tracepoint_active check > * Fix build error reported by kernel test robot. > > Changes in v5: > * Move arm64 to use asm-generic provided high level MMIO accessors (Arnd). > * Add inline logging for MMIO relaxed and non-relaxed accessors. > * Move nVHE KVM comment to makefile (Marc). > * Fix overflow warning due to switch to inline accessors instead of macro. > * Modify trace event field to include caller and parent details for more detailed logs. > > Changes in v4: > * Drop dynamic debug based filter support since that will be developed later with > the help from Steven (Ftrace maintainer). > * Drop value passed to writel as it is causing hangs when tracing is enabled. > * Code cleanup for trace event as suggested by Steven for earlier version. > * Fixed some build errors reported by 0-day bot. > > Changes in v3: > * Create a generic mmio header for instrumented version (Earlier suggested in [1] > by Will Deacon and recently [2] by Greg to have a generic version first). > * Add dynamic debug support to filter out traces which can be very useful for targeted > debugging specific to subsystems or drivers. > * Few modifications to the rwmmio trace event fields to include the mmio width and print > addresses in hex. > * Rewrote commit msg to explain some more about usecases. > > Prasad Sodagudi (1): > lib: Add register read/write tracing support > > Sai Prakash Ranjan (4): > arm64: io: Use asm-generic high level MMIO accessors > irqchip/tegra: Fix overflow implicit truncation warnings > drm/meson: Fix overflow implicit truncation warnings > asm-generic/io: Add logging support for MMIO accessors > > arch/Kconfig | 3 + > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/io.h | 41 +++---------- > arch/arm64/kvm/hyp/nvhe/Makefile | 7 ++- > drivers/gpu/drm/meson/meson_viu.c | 22 +++---- > drivers/irqchip/irq-tegra.c | 10 ++-- > include/asm-generic/io.h | 82 ++++++++++++++++++++++++-- > include/trace/events/rwmmio.h | 97 +++++++++++++++++++++++++++++++ > lib/Kconfig | 7 +++ > lib/Makefile | 2 + > lib/trace_readwrite.c | 47 +++++++++++++++ > 11 files changed, 265 insertions(+), 54 deletions(-) > create mode 100644 include/trace/events/rwmmio.h > create mode 100644 lib/trace_readwrite.c > > > base-commit: bd8d9cef2a7932e688ca267ea1adf5ea6557c777 Any comments on this version? Thanks, Sai